Laboratory Studies For Oil Displacement By Air Injection In Bonan Luo36 Reservoir

The exploiting low permeability and light oil reservoir by air injection is a novel creative technique of enhancing recovery. It is applicable to water flooded oil reservoir for tertiary oil recovery and to low permeable reservoir for secondary oil recovery which is not suitable for water-flood. Air injection can be applied for maintaining reservoir pressure with water flooding,and for gravity drainage. When air is injected into reservoir, there is not only ordinary gas effect, but also other effect of oxidation. The exothermic oxidation reaction between the oil and oxygen is emerged, the oxygen is consumed and carbon oxide is produced, and the heat can make the reservoir temperature increase and make the light component evaporate. Thus air injection in reservoir is a flue-gas displacement which containing carbon dioxide, nitrogen and the evaporating light hydrocarbon component. By researching air injection laboratory testing and field testing at home and abroad, the paper summarizes the mechanism of enhance oil recovery by air injection, also tests and evaluates crude oil oxidation kinetics after contact with the air in different conditions through using high pressure reactor and dynamic displacement device. It tests produced gas constituent and analyzes the affection of oil, temperature and air hold-up time to the oxygen consumption rate. The theoretical basis is provided for numerical reservoir simulation. In the meanwhile, Through the air injection, air foam injection in low-temperature oxidation dynamic displacement experiments, the result indicates that the oil recovery with horizontal displacement by air injection is modest at Bonanluo36 reservoir, average 1-3 percentage points higher than the water drive, but in actual reservoir, may have a certain reservoir declination, oil recovery can be improved by gravity drainage. Moreover, to prevent gas early breakthrough, it injects a certain foam bubble slug to plug high permeability zone, makes oil recovery enhance greatly, enhances oil recovery 30 percent more than the water drive.